Mutations of the PIK3CA gene in human cancers

ABSTRACT

Phosphatidylinositol 3-kinases (PI3Ks) are known to be important regulators of signaling pathways. To determine whether PI3Ks are genetically altered in cancers, we analyzed the sequences of the P13K gene family and discovered that one family member, PIK3CA, is frequently mutated in cancers of the colon and other organs. The majority of mutations clustered near two positions within the P13K helical or kinase domains. PIK3CA represents one of the most highly mutated oncogenes yet identified in human cancers and is useful as a diagnostic and therapeutic target.

This application was made using funds provided by the United States government under grant nos. NIH-CA 62924 and NIH-CA 43460. The United States government therefore retains certain rights in the invention.

FIELD OF THE INVENTION

The invention relates to the fields of diagnostic tests and therapeutic methods for cancer.

BACKGROUND OF THE INVENTION

PI3Ks are lipid kinases that function as signal transducers downstream of cell surface receptors and mediate pathways important for cell growth, proliferation, adhesion, survival and motility (1, 2). Although increased PI3K activity has been observed in many colorectal and other tumors (3, 4), no intragenic mutations of PI3K have been identified.

Members of the PIK3 pathway have been previously reported to be altered in cancers, for example, the PTEN tumor suppressor gene (15, 16), whose function is to reverse the phosphorylation mediated by PI3Ks (17, 18). Reduplication or amplification of the chromosomal regions containing PIK3CA and AKT2 has been reported in some human cancers (2, 19, 20), but the genes that are the targets of such large-scale genetic events have not been and cannot easily be defined.

BRIEF SUMMARY OF THE INVENTION

In a first embodiment a method is provided for assessing cancer in a human tissue suspected of being cancerous of a patient. A non-synonymous, intragenic mutation in a PIK3CA coding sequence is detected in a body sample of a human suspected of having a cancer. The human is identified as likely to have a cancer if a non-synonymous, intragenic mutation in PIK3CA coding sequence is determined in the body sample.

In a second embodiment of the invention a method is provided for inhibiting progression of a tumor in a human. An antisense oligonucleotide or antisense construct is administered to a tumor. The antisense oligonucleotide or RNA transcribed from the antisense construct is complementary to mRNA transcribed from PIK3CA. The amount of p110α protein expressed by the tumor is thereby reduced.

Another embodiment of the invention provides a method of inhibiting progression of a tumor in a human. siRNA comprising 19 to 21 bp duplexes of a human PIK3CA mRNA with 2 nt 3′ overhangs are administered to the human. One strand of the duplex comprises a contiguous sequence selected from mRNA transcribed from PIK3CA (SEQ ID NO: 2). The amount of p110α protein expressed by the tumor is thereby reduced.

According to another aspect of the invention a method is provided for inhibiting progression of a tumor. A molecule comprising an antibody binding region is administered to a tumor. The antibody binding region specifically binds to PIK3CA (SEQ ID NO: 3).

Another embodiment of the invention provides a method of identifying candidate chemotherapeutic agents. A wild-type or activated mutant p110α (SEQ ID NO: 3) is contacted with a test compound. p110α activity is then measured. A test compound is identified as a candidate chemotherapeutic agent if it inhibits p110α activity.

Still another embodiment of the invention is a method for delivering an appropriate chemotherapeutic drug to a patient in need thereof. A non-synonymous, intragenic mutation in a PIK3CA coding sequence (SEQ ID NO: 1) is determined in a test tissue of a patient. A p110α inhibitor is administered to the patient.

An additional aspect of the invention provides a set of one or more primers for amplifying and/or sequencing PIK3CA. The primers are selected from the group consisting of forward primers, reverse primers and sequencing primers. The forward primers are selected from the group consisting of: SEQ ID NO: 6 to 158; the reverse primers are selected from the group consisting of: SEQ ID NO: 159 to 310; and the sequencing primers are selected from the group consisting of: SEQ ID NO: 311 to 461.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Detection of mutations in of PIK3CA. Representative examples of mutations in exons 9 and 20. In each case, the top sequence chromatogram was obtained from normal tissue and the three lower sequence chromatograms from the indicated tumors. Arrows indicate the location of missense mutations. The nucleotide and amino acid alterations are indicated above the arrow.

FIG. 2. Distribution of mutations in PIK3CA. Arrows indicate the location of missense mutations, and boxes represent functional domains (p85BD, p85 binding domain; RBD, Ras binding domain; C2 domain; Helical domain; Kinase domain). The percentage of mutations detected within each region in cancers is indicated below.

FIGS. 3A-3C. Increased lipid kinase activity of mutant p110α. NIH3T3 cells were transfected with empty vector or with vector constructs containing either wild-type p110α or mutant p110α (H1047R) as indicated above the lanes. Immunoprecipitations were performed either with control IgG or anti-p85 polyclonal antibodies. (FIG. 3A) Half of the immunoprecipitates were subjected to a PI3-kinase assay using phosphatidylinositol as a substrate. “PI3P” indicates the position of PI-3-phosphate determined with standard phosphatidyl markers and “Ori” indicates the origin. (FIG. 3B) The other half of the immunoprecipitates was analyzed by western blotting with anti-p110α antibody. (FIG. 3C) Cell lysates from transfected cells contained similar amounts of total protein as determined by western blotting using an anti-α-tubulin antibody. Identical results to those shown in this figure were observed in three independent transfection experiments.

DETAILED DESCRIPTION OF THE INVENTION

The clustering of mutations within PIK3CA make it an excellent marker for early detection or for following disease progression. Testing focused in the clustered regions will yield most of the mutant alleles.

The human PIK3CA coding sequence is reported in the literature and is shown in SEQ ID NO: 1. This is the sequence of one particular individual in the population of humans. Humans vary from one to another in their gene sequences. These variations are very minimal, sometimes occurring at a frequency of about 1 to 10 nucleotides per gene. Different forms of any particular gene exist within the human population. These different forms are called allelic variants. Allelic variants often do not change the amino acid sequence of the encoded protein; such variants are termed synonymous. Even if they do change the encoded amino acid (non-synonymous), the function of the protein is not typically affected. Such changes are evolutionarily or functionally neutral. When human PIK3CA is referred to in the present application all allelic variants are intended to be encompassed by the term. The sequence of SEQ ID NO: 1 is provided merely as a representative example of a wild-type human sequence. The invention is not limited to this single allelic form of PIK3CA. For purposes of determining a mutation, PIK3CA sequences determined in a test sample can be compared to a sequence determined in a different tissue of the human. A difference in the sequence in the two tissues indicates a somatic mutation. Alternatively, the sequence determined in a PIK3CA gene in a test sample can be compared to the sequence of SEQ ID NO: 1. A difference between the test sample sequence and SEQ ID NO: 1 can be identified as a mutation. Tissues suspected of being cancerous can be tested, as can body samples that may be expected to contain sloughed-off cells from tumors or cells of cancers. Suitable body samples for testing include blood, serum, plasma, sputum, urine, stool, nipple aspirate, saliva, and cerebrospinal fluid.

Mutations in PIK3CA cluster in exons 9 (SEQ ID NO: 4) and 20 (SEQ ID NO: 5). Other mutations occur, but these two exons appear to be the hotspots for mutations. Many mutations occur in PIK3CA's helical domain (nt 1567-2124 of SEQ ID NO: 2) and in its kinase domain (nt 2095-3096 of SEQ ID NO: 2). Fewer occur in PIK3CA's P85BD domain (nt 103-335 of SEQ ID NO: 2). Mutations have been found in exons 1, 2, 4, 5, 7, 9, 13, 18, and 20. Any combination of these exons can be tested, optionally in conjunction with testing other exons. Testing for mutations can be done along the whole coding sequence or can be focused in the areas where mutations have been found to cluster. Particular hotspots of mutations occur at nucleotide positions 1624, 1633, 1636, and 3140 of PIK3CA coding sequence.

PIK3CA mutations have been found in a variety of different types of tumors. Thus any of a variety of tumors can be tested for PIK3CA mutations. These tissues include, without limitation: colorectal tissue, brain tissue, gastric tissue, breast tissue, and lung tissue.

Any type of intragenic mutation can be detected. These include substitution mutations, deletion mutations, and insertion mutations. The size of the mutations is likely to be small, on the order of from 1 to 3 nucleotides. Mutations which can be detected include, but are not limited to G1624A, G1633A, C1636A, A3140G, G113A, T1258C, G3129T, C3139T, and G2702T. Any combination of these mutations can be tested.

The mutations that are found in PIK3CA appear to be activating mutations. Thus therapeutic regimens involving inhibition of p110α activity or expression can be used to inhibit progression of a tumor in a human. Inhibitory molecules which can be used include antisense oligonucleotides or antisense constructs, a molecule comprising an antibody binding region, and siRNA molecules. Molecules comprising an antibody binding region can be full antibodies, single chain variable regions, antibody fragments, antibody conjugates, etc. The antibody binding regions may but need not bind to epitopes contained within the kinase domain (nt 2095-3096 of SEQ ID NO: 2) of PIK3CA, the helical domain (nt 1567-2124 of SEQ ID NO: 2) of PIK3CA, or the P85BD domain (nt 103-335 of SEQ ID NO: 2) of PIK3CA.

Antisense constructs, antisense oligonucleotides, RNA interference constructs or siRNA duplex RNA molecules can be used to interfere with expression of PIK3CA. Typically at least 15, 17, 19, or 21 nucleotides of the complement of PIK3CA mRNA sequence are sufficient for an antisense molecule. Typically at least 19, 21, 22, or 23 nucleotides of PIK3CA are sufficient for an RNA interference molecule. Preferably an RNA interference molecule will have a 2 nucleotide 3′ overhang. If the RNA interference molecule is expressed in a cell from a construct, for example from a hairpin molecule or from an inverted repeat of the desired PIK3CA sequence, then the endogenous cellular machinery will create the overhangs. siRNA molecules can be prepared by chemical synthesis, in vitro transcription, or digestion of long dsRNA by Rnase III or Dicer. These can be introduced into cells by transfection, electroporation, or other methods known in the art. See Hannon, G J, 2002, RNA Interference, Nature 418: 244-251; Bernstein E et al., 2002, The rest is silence. RNA 7: 1509-1521; Hutvagner G et al., RNAi: Nature abhors a double-strand. Curr. Opin. Genetics & Development 12: 225-232; Brummelkamp, 2002, A system for stable expression of short interfering RNAs in mammalian cells. Science 296: 550-553; Lee N S, Dohjima T, Bauer G, Li H, Li M-J, Ehsani A, Salvaterra P, and Rossi J. (2002). Expression of small interfering RNAs targeted against HIV-1 rev transcripts in human cells. Nature Biotechnol. 20:500-505; Miyagishi M, and Taira K. (2002). U6-promoter-driven siRNAs with four uridine 3′ overhangs efficiently suppress targeted gene expression in mammalian cells. Nature Biotechnol. 20:497-500; Paddison P J, Caudy A A, Bernstein E, Hannon G J, and Conklin D S. (2002). Short hairpin RNAs (shRNAs) induce sequence-specific silencing in mammalian cells. Genes & Dev. 16:948-958; Paul C P, Good P D, Winer I, and Engelke D R. (2002). Effective expression of small interfering RNA in human cells. Nature Biotechnol. 20:505-508; Sui G, Soohoo C, Affar E-B, Gay F, Shi Y, Forrester W C, and Shi Y. (2002). A DNA vector-based RNAi technology to suppress gene expression in mammalian cells. Proc. Natl. Acad. Sci. USA 99(6):5515-5520; Yu J-Y, DeRuiter S L, and Turner D L. (2002). RNA interference by expression of short-interfering RNAs and hairpin RNAs in mammalian cells. Proc. Natl. Acad. Sci. USA 99(9):6047-6052.

Antisense or RNA interference molecules can be delivered in vitro to cells or in vivo, e.g., to tumors of a mammal. Typical delivery means known in the art can be used. For example, delivery to a tumor can be accomplished by intratumoral injections. Other modes of delivery can be used without limitation, including: intravenous, intramuscular, intraperitoneal, intraarterial, local delivery during surgery, endoscopic, subcutaneous, and per os. In a mouse model, the antisense or RNA interference can be adminstered to a tumor cell in vitro, and the tumor cell can be subsequently administered to a mouse. Vectors can be selected for desirable properties for any particular application. Vectors can be viral or plasmid. Adenoviral vectors are useful in this regard. Tissue-specific, cell-type specific, or otherwise regulatable promoters can be used to control the transcription of the inhibitory polynucleotide molecules. Non-viral carriers such as liposomes or nanospheres can also be used.

Using the p110α protein according to the invention, one of ordinary skill in the art can readily generate antibodies which specifically bind to the proteins. Such antibodies can be monoclonal or polyclonal. They can be chimeric, humanized, or totally human. Any functional fragment or derivative of an antibody can be used including Fab, Fab′, Fab2, Fab′2, and single chain variable regions. So long as the fragment or derivative retains specificity of binding for the endothelial marker protein it can be used. Antibodies can be tested for specificity of binding by comparing binding to appropriate antigen to binding to irrelevant antigen or antigen mixture under a given set of conditions. If the antibody binds to the appropriate antigen at least 2, 5, 7, and preferably 10 times more than to irrelevant antigen or antigen mixture then it is considered to be specific.

Techniques for making such partially to fully human antibodies are known in the art and any such techniques can be used. According to one particularly preferred embodiment, fully human antibody sequences are made in a transgenic mouse which has been engineered to express human heavy and light chain antibody genes. Multiple strains of such transgenic mice have been made which can produce different classes of antibodies. B cells from transgenic mice which are producing a desirable antibody can be fused to make hybridoma cell lines for continuous production of the desired antibody. See for example, Nina D. Russel, Jose R. F. Corvalan, Michael L. Gallo, C. Geoffrey Davis, Liise-Anne Pirofski. Production of Protective Human Antipneumococcal Antibodies by Transgenic Mice with Human Immunoglobulin Loci Infection and Immunity April 2000, p. 1820-1826; Michael L. Gallo, Vladimir E. Ivanov, Aya Jakobovits, and C. Geoffrey Davis. The human immunoglobulin loci introduced into mice: V (D) and J gene segment usage similar to that of adult humans European Journal of Immunology 30: 534-540, 2000; Larry L. Green. Antibody engineering via genetic engineering of the mouse: XenoMouse strains are a vehicle for the facile generation of therapeutic human monoclonal antibodies Journal of Immunological Methods 231 11-23, 1999; Yang X-D, Corvalan J R F, Wang P, Roy C M-N and Davis C G. Fully Human Anti-interleukin-8 Monoclonal Antibodies: Potential Therapeutics for the Treatment of Inflammatory Disease States. Journal of Leukocyte Biology Vol. 66, pp 401-410 (1999); Yang X-D, Jia X-C, Corvalan J R F, Wang P, C G Davis and Jakobovits A. Eradication of Established Tumors by a Fully Human Monoclonal Antibody to the Epidermal Growth Factor Receptor without Concomitant Chemotherapy. Cancer Research Vol. 59, Number 6, pp1236-1243 (1999); Jakobovits A. Production and selection of antigen-specific fully human monoclonal antibodies from mice engineered with human Ig loci. Advanced Drug Delivery Reviews Vol. 31, pp: 33-42 (1998); Green L and Jakobovits A. Regulation of B cell development by variable gene complexity in mice reconstituted with human immunoglobulin yeast artificial chromosomes. J. Exp. Med. Vol. 188, Number 3, pp: 483-495 (1998); Jakobovits A. The long-awaited magic bullets: therapeutic human monoclonal antibodies from transgenic mice. Exp. Opin. Invest. Drugs Vol. 7(4), pp: 607-614 (1998); Tsuda H, Maynard-Currie K, Reid L, Yoshida T, Edamura K, Maeda N, Smithies O, Jakobovits A. Inactivation of Mouse HPRT locus by a 203-bp retrotransposon insertion and a 55-kb gene-targeted deletion: establishment of new HPRT-Deficient mouse embryonic stem cell lines. Genomics Vol. 42, pp: 413-421 (1997); Sherman-Gold, R. Monoclonal Antibodies: The Evolution from '80s Magic Bullets To Mature, Mainstream Applications as Clinical Therapeutics. Genetic Engineering News Vol. 17, Number 14 (August 1997); Mendez M, Green L, Corvalan J, Jia X-C, Maynard-Currie C, Yang X-d, Gallo M, Louie D, Lee D, Erickson K, Luna J, Roy C, Abderrahim H, Kirschenbaum F, Noguchi M, Smith D, Fukushima A, Hales J, Finer M, Davis C, Zsebo K, Jakobovits A. Functional transplant of megabase human immunoglobulin loci recapitulates human antibody response in mice. Nature Genetics Vol. 15, pp: 146-156 (1997); Jakobovits A. Mice engineered with human immunoglobulin YACs: A new technology for production of fully human antibodies for autoimmunity therapy. Weir's Handbook of Experimental Immunology, The Integrated Immune System Vol. IV, pp: 194.1-194.7 (1996); Jakobovits A. Production of fully human antibodies by transgenic mice. Current Opinion in Biotechnology Vol. 6, No. 5, pp: 561-566 (1995); Mendez M, Abderrahim H, Noguchi M, David N, Hardy M, Green L, Tsuda H, Yoast S, Maynard-Currie C, Garza D, Gemmill R, Jakobovits A, Klapholz S. Analysis of the structural integrity of YACs comprising human immunoglobulin genes in yeast and in embryonic stem cells. Genomics Vol. 26, pp: 294-307 (1995); Jakobovits A. YAC Vectors: Humanizing the mouse genome. Current Biology Vol. 4, No. 8, pp: 761-763 (1994); Arbones M, Ord D, Ley K, Ratech H, Maynard-Curry K, Otten G, Capon D, Tedder T. Lymphocyte homing and leukocyte rolling and migration are impaired in L-selectin-deficient mice. Immunity Vol. 1, No. 4, pp: 247-260 (1994); Green L, Hardy M, Maynard-Curry K, Tsuda H, Louie D, Mendez M, Abderrahim H, Noguchi M, Smith D, Zeng Y, et. al. Antigen-specific human monoclonal antibodies from mice engineered with human Ig heavy and light chain YACs. Nature Genetics Vol. 7, No. 1, pp: 13-21 (1994); Jakobovits A, Moore A, Green L, Vergara G, Maynard-Curry K, Austin H, Klapholz S. Germ-line transmission and expression of a human-derived yeast artificial chromosome. Nature Vol. 362, No. 6417, pp: 255-258 (1993); Jakobovits A, Vergara G, Kennedy J, Hales J, McGuinness R, Casentini-Borocz D, Brenner D, Otten G. Analysis of homozygous mutant chimeric mice: deletion of the immunoglobulin heavy-chain joining region blocks B-cell development and antibody production. Proceedings of the National Academy of Sciences USA Vol. 90, No. 6, pp: 2551-2555 (1993); Kucherlapati et al., U.S. Pat. No. 6,1075,181.

Antibodies can also be made using phage display techniques. Such techniques can be used to isolate an initial antibody or to generate variants with altered specificity or avidity characteristics. Single chain Fv can also be used as is convenient. They can be made from vaccinated transgenic mice, if desired. Antibodies can be produced in cell culture, in phage, or in various animals, including but not limited to cows, rabbits, goats, mice, rats, hamsters, guinea pigs, sheep, dogs, cats, monkeys, chimpanzees, apes.

Antibodies can be labeled with a detectable moiety such as a radioactive atom, a chromophore, a fluorophore, or the like. Such labeled antibodies can be used for diagnostic techniques, either in vivo, or in an isolated test sample. Antibodies can also be conjugated, for example, to a pharmaceutical agent, such as chemotherapeutic drug or a toxin. They can be linked to a cytokine, to a ligand, to another antibody. Suitable agents for coupling to antibodies to achieve an anti-tumor effect include cytokines, such as interleukin 2 (IL-2) and Tumor Necrosis Factor (TNF); photosensitizers, for use in photodynamic therapy, including aluminum (III) phthalocyanine tetrasulfonate, hematoporphyrin, and phthalocyanine; radionuclides, such as iodine-131 (¹³¹I), yttrium-90 (⁹⁰Y), bismuth-212 (²¹²Bi), bismuth-213 (²¹³Bi), technetium-99m (^(99m)Tc), rhenium-186 (¹⁸⁶Re), and rhenium-188 (¹⁸⁸Re); antibiotics, such as doxorubicin, adriamycin, daunorubicin, methotrexate, daunomycin, neocarzinostatin, and carboplatin; bacterial, plant, and other toxins, such as diphtheria toxin, pseudomonas exotoxin A, staphylococcal enterotoxin A, abrin-A toxin, ricin A (deglycosylated ricin A and native ricin A), TGF-alpha toxin, cytotoxin from chinese cobra (naja naja atra), and gelonin (a plant toxin); ribosome inactivating proteins from plants, bacteria and fungi, such as restrictocin (a ribosome inactivating protein produced by Aspergillus restrictus), saporin (a ribosome inactivating protein from Saponaria officinalis), and RNase; tyrosine kinase inhibitors; ly207702 (a difluorinated purine nucleoside); liposomes containing antitumor agents (e.g. antisense oligonucleotides, plasmids which encode for toxins, methotrexate, etc.); and other antibodies or antibody fragments, such as F(ab).

Those of skill in the art will readily understand and be able to make such antibody derivatives, as they are well known in the art. The antibodies may be cytotoxic on their own, or they may be used to deliver cytotoxic agents to particular locations in the body. The antibodies can be administered to individuals in need thereof as a form of passive immunization.

Given the success of small molecule protein kinase inhibitors, one can develop specific or non-specific inhibitors of p110α for treatment of the large number of patients with these mutations or cancers generally. It is clearly possible to develop broad-spectrum PI3K inhibitors, as documented by studies of LY294002 and wortmannin (2, 21, 22). Our data suggest that the development of more specific inhibitors that target p110α but not other PI3Ks would be worthwhile.

Candidate chemotherapeutic agents can be identified as agents which inhibit p110α activity or expression. Test compounds can be synthetic or naturally occurring. They can be previously identified to have physiological activity or not. Tests on candidate chemotherapeutic agents can be run in cell-free systems or in whole cells. p110α activity can be tested by any means known in the art. These include methods taught in references 2, 22 and in Truitt et al., J. Exp. Med., 179, 1071-1076 (1994). Expression can be monitored by determining PI3KCA protein or mRNA. Antibody methods such as western blotting can be used to determine protein. Northern blotting can be used to measure mRNA. Other methods can be used without limitation. When testing for chemotherapeutic agents, the p110α used in the assay can be a wild-type or an activated form. The activated form may contain a substitution mutation selected from the group consisting of E542K, E545K, Q546K, and H1047R. Moreover, inhibitors can be tested to determine their specificity for either p110α or an activated form of p110α. Comparative tests can be run against similar enzymes including PIK3CB, PIK3CG, PIK3C2A, PIK3C2B, PIK3C2G, PIK3C3, A-TM, ATR, FRAP1, LAT1-3TM, SMG1, PRKDC, and TRRAP to determine the relative specificity for the p110α enzyme.

Once a non-synonymous, intragenic mutation in a PIK3 CA coding sequence is identified in a test tissue of a patient, that information can be used to make therapeutic decisions. Patients with such mutations are good candidates for therapy with a p110α inhibitor. Such inhibitors can be specific or general for the family of inhibitors. Such inhibitors include LY294002 and wortmannin. Such inhibitors further include molecules comprising an antibody binding region specific for p110α. Such molecules are discussed above.

Sets of primers for amplifying and/or sequencing PIK3CA can be provided in kits or assembled from components. Useful sets include pairs of forward and reverse primers optionally teamed with sequencing primers. The forward primers are shown in SEQ ID NO: 6 to 158. The reverse primers are shown in SEQ ID NO: 159 to 310. The sequencing primers are shown in: SEQ ID NO: 311 to 461. Pairs or triplets or combinations of these pairs or triplets can be packaged and used together to amplify and/or sequence parts of the PIK3CA gene. Pairs can be packaged in single or divided containers. Instructions for using the primers according to the methods of the present invention can be provided in any medium which is convenient, including paper, electronic, or a world-wide web address.

While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims.

EXAMPLES Example 1 This Example Demonstrates that the PIK3CA Gene is the Predominant Target of Mutations in this Gene Family

To evaluate whether PI3Ks is genetically implicated in tumorigenesis, we directly examined the DNA sequences of members of this gene family in colorectal cancers.

PI3K catalytic subunits are divided into three major classes depending on their substrate specificity (5). Additionally, a set of more distantly related proteins, including members of the mTOR family, constitute a fourth class (6). We used Hidden Markov models to identify 15 human genes containing kinase domains related to those of known PI3Ks in the human genome (7). These comprised seven PI3Ks, six members of the mTOR subfamily and two uncharacterized PI3K-like genes (Table 1).

TABLE 1 PI3K genes analyzed Celera Genbank Gene name Accession Accession Alternate names Group* PIK3CA hCT1640694 NM_006218 p110-alpha Class IA PIK3CB hCT7084 NM_006219 PIK3C1, p110-beta Class IA PIK3CD hCT2292011 NM_005026 p110-delta Class IA PIK3CG hCT7976 NM_002649 PI3CG, PI3K-gamma Class IB PIK3C2A hCT2270768 NM_002645 CPK, PI3-K-C2A, PI3K-C2alpha Class II PIK3C2B hCT7448 NM_002646 C2-PI3K, PI3K-C2beta Class II PIK3C2G hCT1951422 NM_004570 PI3K-C2-gamma Class II PIK3C3 hCT13660 NM_002647 Vps34 Class III ATM hCT29277 NM_000051 AT1, ATA, ATC, ATD, ATE, ATDC Class IV ATR hCT1951523 NM_001184 FRP1, SCKL, SCKL1 Class IV FRAP1 hCT2292935 NM_004958 FRAP, MTOR, FRAP2, RAFT1, RAPT1 Class IV SMG1 hCT2273636 NM_014006 ATX, LIP, KIAA0421 Class IV PRKDC hCT2257127 NM_006904 p350, DNAPK, DNPK1, HYRC1, XRCC7 Class IV TRRAP hCT32594 NM_003496 TR-AP, PAF400 Class IV none hCT2257641 none Class IV none hCT13051 none Class IV *PI3K genes are grouped into previously described classes (S3, S4). Class I, II and III comprise PI3K catalytic subunits, while class IV comprises PI3K-like genes including members of the mTOR (target of rapamycin), ATM (ataxia telangiectasia mutated), and DNAPK (DNA-dependent protein kinase) subfamilies, as well as two previously uncharacterized genes.

We initially examined 111 exons encoding the predicted kinase domains of these genes (Table 2). The exons were polymerase chain reaction (PCR) amplified and directly sequenced from genomic DNA of 35 colorectal cancers (8). Only one of the genes (PIK3CA) contained any somatic (i.e., tumor-specific) mutations.

TABLE 2 Primers used for PCR amplification and sequencing Gene and Exon Name Forward Primer¹ Reverse primer² Sequencing Primer³ hCT2270768-Ex21 TTCCAGCCTGGGTAACAAAG CGTCAGAACAAGACCCTGTG AAAGGGGAAATGCGTAGGAC hCT2270768-Ex22 CCTGACCTCAGGTGTTCTGC CCCGGCCACTAAGTTATTTTTC TCCCAAAGTGCTGGGATTAC hCT2270768-Ex23 TGCACATTCTGCACGTGTATC CTGCCATTAAATGCGTCTTG CCAGAACTTAAAGTGAAATTTAAAAAG hCT2270768-Ex24 TCCCAGTTTGTATGCTATTGAGAG CTTTGGGCCTTTTTCATTCC GCGAGGCAAAACACAAAGC hCT2270768-Ex25 TGGAAATTCAAAAGTGTGTGG TGTCTGGCTTATTTCACACG TTGGAAATGGCTGTACCTCAG hCT2270768-Ex26 CACTAATGAACCCCTCAAGACTG AACTTTTGACAGCCTACTATGTGC TACTTGAGCAGCCCACAGG hCT2270768-Ex27-1 TCCTTGGCAAAGTGACAATC GACCATTCATGAAAGAAACAAGC AAAGGAATGAAAGTGGTTTTTGTC hCT13660-Ex16 CTCTCACATACAACACCATCTCC CCATGTACCGGTAACAAAAGAAG TGCAATGTAATAGTTTTCCAAGG hCT13660-Ex17 ATGTATCTCATTGAAAACCCAAC TGAGCTTTCTAGGATCGTACCTG CAGCAAATGAACTAAGCCACAG hCT13660-Ex18 TCCCAAAGTGCTGGGATTAC GCAGGAAGGTCCAACTTGTC TGCTATACTATTTGCCCACAAAAC hCT13660-Ex19 CCTATGACATAAATGCCAGTACAAAC ATCTTCAACTGCGAACATGC GAATGCATTTATTCAGAGATGAGG hCT13660-Ex20 TCTTTTGTTCAGTCAGCATCTCTC AAGCATCAATGACTACTTTAATCAAC TGCTAGACACTTGCTGGTCAC hCT13660-Ex21 TTGAGAATTCAGATGAGAAACCAG TCCCAAAGTGCTGGGATTAC TTGATATTAAAGTTGCACAAACTGC hCT13660-Ex22 GAAGGCCACTCTCAAACCTG TTGTTGCCTTTGTCATTTTG TCAATTGTGTGACATATCACCTACC hCT13660-Ex23 TCAAGGCTTGCATTTCATTG ATGTGACTGTGGGCAGGAAC TCACTGTAGAAATCCAAGTACCAC hCT13660-Ex24 TTCCACACTCCAAAGAATGC GCTGGTGAGATGTCAAAACG TCTGCATCAGTTTGATTCTGC hCT13660-Ex25-1 AATTGCAATCCTCTTGGTAGC TCAACATATTACTTCCTCCAGAAGTC AATGCACTTTTTATTTTATTAG hCT32594-Ex66-2 GCCAAGACCAAGCAACTCC TTCTCCCATGTCAGGGAATC GAAAAGTGCCGGTTCTTGAG hCT32594-Ex67-1 ATAAACGACCGCTGGCCTAC GACCCTCAAAGGCTAACGTG GCCTACACAGTCCGTTTTCC hCT32594-Ex67-2 GTACATCCGGGGACACAATG TCCCTGGTCAGCACAGACTAC AGAGGAGCGTGTGTTGCAG hCT32594-Ex68 ACCGGGTTCTTCCAGCTAAG AGCTGTCTCATTTCCACCATC ACTCTGACGGTGGAGCTGAG hCT32594-Ex69-1 CAATGCGTGCGTTAAATCTG CGCGTCGTTTATGTCAAATC GCTCTTGGTGCTAAGTTAAAGAGG hCT32594-Ex69-2 CCCAATGCCACGGACTAC CGCGTCGTTTATGTCAAATC ATCCAGCTGGCTCTGATAGG hCT32594-Ex70 ATCCAGCTGGCTCTGATAGG CATAACACACAGGGGTGCTG TGAACAGCCAGATCCTCTCC hCT32594-Ex71 CTGGTGCTGAAACTCGACTG GAACTGGGCGAGGTTGTG GTCCCACCTTGTTAGGAAGC hCT32594-Ex72-1 GTCTCGTTCTCTCCCTCACG TCCCTTTCTTACACGCAAAC TGGCATTCTGAAAACGGTTC hCT32594-Ex72-2 CACAACCTCGCCCAGTTC CAGTTCCGCCTGTACATTCAC GCAAACAGCCTGGACAATC hCT7976-Ex5 AGCATCACCCTCAGAGCATAC AGCGCTCCTGCTTTCAGTC CACATATTTCTGTCCCCTGTTG hCT7976-Ex6 TGCCATACCTCTTAGGCACTTC GTCTTGGCGCAGATCATCAC TGTGGTTCTTTGGAGCACAG hCT7976-Ex7 CGACAGAGCAAGATTCCATC TTTTGTCACCAGTTGAAATGC CCAAGGTACATTTCGGAAAAC hCT7976-Ex8 AGATTGCCATCTGAGGAAGG GACTGGGAAAAAGCATGAGC ACCAGCCCTTTCCTCTTGTC hC17976-Ex9 GCATGGAGAGGAAGTGAACC CGGTGATCATAATATTGTCATTGTG TTCTTCCTCATGCCATTGTG hCT7976-Ex10 TGGCCAGAGAGTTTGATTTATG GGAAGTGTGGGCTTGTCTTC GTGGCATCTGGCTGTCATC hCT7976-Ex11-1 CCCTCAATCTCTTGGGAAAG TGCACAGTCCATCCTTTGTC CAATTAGTTTTCCTTGAGCACTCC hCT7976-Ex11-2 TGGTTTCTTCTCATGGACAGG AATGCCAGCTTTCACAATGTC TCTTCTTTATCCAGGACATCTGTG hCT7448-Ex21 GGGTGTCCACACTTCTCAGG GGCCAAGACCACATGGTAAG CCTGGGAGAGGTCTGGTTC hCT7448-Ex22 CCGGAAGAAACAATGAGCAG TCCTACATTAAGACAGCATGGAAC GGCAGCATCTTGGTCTGAAG hCT7448-Ex23 GGTGTGAGCTGAGTGAGCAG TGCCTCCCTTTTAAGGCTATC GAGCACTTGGGAGACCTGAG hCT7448-Ex24 GTGGGAATGACCTTCCTTTC AGGTCCTTCTGCCAACAAAG AGGGAAGCATGAGCACAGTC hC17448-Ex25 GGATGAACAGGCAGATGTGAG CGTCTTCTCTCCTCCAATGC TGAGTTCTGTCTGGCTGTGG hCT7448-Ex26 AGCCCCTTCTATCCAGTGTG GGTATTCAGTTGGGGCTCAG TGATGAGGGATGAGGGAAAC hCT7448-Ex27 TGCCCACAGCATCTGTCTAC TGTATCCACGTGGTCAGCTC AGGGTTAGGGAGCCTAGCTG hCT7448-Ex28-1 ATTGTGTGCCAGTCATTTGC ACAGGACGCTCGGTCAAC TCCTTGGAACACCCCTGTC hCT1951523-Ex39-2 TTCCACATTAAGCATGAGCAC TTGCCATCAGTACAAATGAGTTTAG CAGTCATGATACCTACACTTCCATC hCT1951523-Ex40 GACAGTCATTCTTTTCATAGGTCATAG TTCCTGCTTTTTAAGAGTGATCTG CAACTCTGAAATAAAAGCAATCTGG hCT1951523-Ex41 CCACATAGTAAGCCTTCAATGAC AGGAAGGAAGGGATGGAAAC TTCTTTGGTTATGAAATGAACAATC hCT1951523-Ex42 TGAAAAATGTTCCTTTATTCTTG AGAAACCACTCATGAAAA TTGAATAAAAGTAGATGTTTCTTGTCC hCT1951523-Ex43 TCTGAGAACATTCCCTGATCC CGCATTACTACATGATCCACTG TACCAAGAATATAATACGTTGTTATGG hCT2257127-Ex76 TCAGCTCTCTAATCCTGAACTGC TGTCACAGAAAGCATGAGACC CGGCTTCTGGCACATAAAAC hCT2257127-Ex77-1 AGCAGAGAAGAAACATATACCAT AGAAATAACTGTCAATATCCCAGTATCAC CCATTGAGCACTCCATTCATTAC hCT2257127-Ex77-2 CATTTTGGGAAAGGAGGTTC TCATTAAACATTTAGTAATGTGTGCTC CCCTGGGAATCTGAAAGAATG hCT2257127-Ex78 ATTACAGGCGTGAGCCACTG AGGCAACAGGGCAAGACTC TGGGCCGTTGTCTCATATAC hCT2257127-Ex79-1 TTTGGCACTGTCTTCAGAGG CCTGAAAGGGAGAATAAAAGG CACTCTGGCTTTCCCTCTG hCT2257127-Ex79-2 AGAGGGAACACCCTTTCCTG CCTGAAAGGGAGAATAAAAGG AGGTCATGAATGGGATCCTG hCT2257127-Ex80 TATAGCGTTGTGCCCATGAC TATTGACCCAGCCAGCAGAC CATATTGCTTGGCGTCCAC hCT2257127-Ex81 TCCTGCCTCTTTGCTATTTTTCAATG TATATTGAGACTCAAATATCGA TCTTGGTGATCTTTGCCTTTG hCT2257127-Ex82 TTGCCTCAGAGAGATCATCAAG TGATGCATATCAGAGCGTGAG TCATCAAGATTATTCGATATTTGAGTC hCT2257127-Ex83-1 TAGGGGCGCTAATCGTACTG TTCAATGACCATGACAAAACG CGAGAAAGTAAAGTGCCTGCTG hCT2257127-Ex83-2 TCTGATATGCATCAGCCACTG TTCAATGACCATGACAAAACG CGGGATTGGAGACAGACATC hCT2257127-Ex84 TGATTTCAAGGGAAGCAGAG TGGTTTTCAAGCAGACAATCC GAGGATGCTGCCATTTGTG hCT2257127-Ex85 TGTAGAAAGCAAGGCTGCTC TCCTCCTCAATGAAAGCAGAG CATGCTAACAGAGTGTCAAGAGC hCT1951422-Ex19 ACCCCAAAGTCATCCAAGTG CAATGTGATCCCAACTGGTC CGAATTCTTTTTGCCATTTC hCT1951422-Ex20 AAAGGCTCCAGTTGATGGAC TTATTGCCAATTGGAGTTTGG AAAGTCTGCAAGGGGCTATG hCT1951422-Ex21 CCATTAAAACCACTCTAAGTCAGG TTCTGTTGGCTTATCATTTTTG TCAGGCTAGAAATGTATCCAAGG hCT1951422-Ex22 AAGCCTCCTCCAGAAAAGAAG CCCAGAAACTAAATAAAATGCAG AAAGGAAAGGGGTAATCCAG hCT1951422-Ex23 CCCTCCTGTCCACTGAGATG AATCAAATTTGTTGCATTAAAAATC TTTACTTTTTATGATTACCTCTGATGC hCT1951422-Ex24 TCTCAAGCTGCCTCACAATG GTTTTCTCATTCCTTTCTCTTCC AAAGAAAATTCAAATGAAAATAAGTCG hCT1951422-Ex25 AAAGACATTGCCATGCAAAC TTTGGGAAAGGGAACACAAG CATGCAAACTTGGGTCTAGATG hCT1951422-Ex26 TTGTTGGGCTCCAAATAAAC GATTTTTCCTTGGAACATCCTC TTGGCTTTTCCCCTCATAC hCT13051-Ex5 CCCTGGAGTGCTTACATGAG CGGGGATCAGATTTGCTATG TAAAGCCTTTCCCAGCTCAG hCT13051-Ex6 GACTTTATAAACACTCGACATTAGAGC TAGGGGGTCATCCTCAGGTG CCTGCTGCTTCCACAGGAC hCT13051-Ex7 ATGATGACCTCTGGCAGGAC GTCTTCCCCTGCTCAATCAC CATGGACGTCCTGTGGAAG hCT13051-Ex8 GAATCAACCGTCAGCGTGTC GACACGTTGTGGGCCAGCCAGT GTGTCCCATTCATCCTCACC hCT13051-Ex9 CTGGCACCGGGGAAAACAGAG CTGCCGGTTATCTTCGGACACGTT AACAGAGGAGGCGCTGAAG hCT2282983-Ex40 TGGACATCGACTACAAGTCTGG TGAGTGAGGGCAGACAGATG GCCTCACCCTACCCATCC hCT2282983-Ex41 TCCTTGGGGTTTTGAAGAAG TGGCACCTGAACCATGTAAG AGATTGCTGGGGTTCCTTTC hCT2282983-Ex42 AAGGCCTTCCAGACTCTTGC CGTACATGCCGAAGTCTGTC CCACCTCACTCCATCTCTGG hCT2282983-Ex43 CCTCTTTGTTTTTCCCTACCG GCCCTGGTTTTAACCCTTAAC TGGGGTAAGTTCCCTGAGTG hCT2282983-Ex44-1 CTTCCACAGTGGGGGTACAG CCAGCTCCAGCTTCTGACTC TACAGAGCCAGGGAGAGTGC hCT2282983-Ex44-2 GACACAACGGCAACATTATGCTG TTGTGTTTTCTTGGAGACAG TATCATCCACATCGGTCAGC hCT2292935-Ex46 CATTCCAAAGCATCTGGTTTTAC CAATGAGCATGGGAGAGATG TTTGGGACAAGTAATTGTTATTAGC hCT2292935-Ex47 TTGTGAGGAACGTGTGATTAGG TGGAGTTTCTGGGACTACAGG TTGAATGCAGTGGTGCTCTC hCT2292935-Ex48 CTGGGCAACAGAGCAAGAC CCTTCTTCAAAGCTGATTCTCTC TCTGCCTGTGTTCTGAGCTG hCT2292935-Ex49 TCCCTTCTCCTTTGGCTATG CGCTCTACAGCCAATCACAG GAACTCAGCTCTGCCTGGAC hCT2292935-Ex50 ATAGCACCACTGCCTTCCAG TGGCATCACAATCAATAGGG GCGAGACTCGGTCTCAAAAG hCT2292935-Ex51 TGCAGAAGTGGAGGTGGAG CTCCAAGGGGGTTAGAGTCC ATCGTTTGCCAACTCCTAGC hCT2292935-Ex52 AACCCAAGCTGCTTCCTTTC CAGGAAACCAGGTCAGAAGTG AATCAGTGCAGGTGATGCAG hCT2292935-Ex53 AGTCCTGCCCTGATTCCTTC TTTTTGCAGAAAGGGGTCTTAC ACATGGCCTGTGTCTGCTTC hCT2292935-Ex54 CCCACCCACTTATTCCTGAG GCCCACCCCACTCTAGAAAC GACTGGAAGAAAATAACCAAGTTTC hCT2292935-Ex55 TTTCCCCTTTAGGGTAGGTAGG TGGAACCTTTTCTGCTCAAAG GGCAGGCGTTAAAGGAATAG hCT2292935-Ex56 CGGACATAGAGGAAGGATTGC AGCTGCATGGTGCCAAAG AAAAACAGGGCACCCATTG hCT2292935-Ex57 TGGCCAAACTTTTCAAATCC ATAACAATGGGCACATGCAG TTAAGCCCACAGGGAACAAG hCT2292935-Ex58-1 TGGGAGAGCTCAGGGAATAC GGTCATTCTTCCATCAGCAAG TGTGAGACCTTGGCCTTTTC hCT2273636-Ex35-1 TCCCAAAGTGCTGGGATTAC CACACCCACACTCAGACAAAG TCTTCTGAAAAATGGAGGAAGTC hCT2273636-Ex35-2 TTGGCTGCCATGACTAACAC GGCACTGCAGGCTAATAATG GCTCTTCCTGGGGAAGTCTC hCT2273636-Ex36-1 GCTCTCAGTGTGCCTCATGG GGGACGTCAAGTCTTTTCCTTC CAGTTTTTGACTGCCACTGC hCT2273636-Ex36-2 AAGAAACACCCCGGTTCC GGGACCTCAAGTCTTTTCCTTG TCCATGCTCGACACTATTCTG hCT2273636-Ex37-1 AAATTTAGTTGAGTAATGAGAGAATGC GGAAGGGAAGGAGGACAAAC TTCTACTTTACATACAAAAGGCACTC hCT2273636-Ex37-2 GTAAAATTGGCCCTGCTTTG CGTCTCAAACTACCAAGTCTGG AGTTGGGCTTAGCCTGGATG hCT2273636-Ex38 CATAACCACATGCAGCAACC CACCCAGTGCTGTTTCAATG AGTATCACGTCCATGTTGGAG hCT2273636-Ex39 AATTGGCCTTGGAGACAGAC CGCCGCATAATGTGTAAAAC CAATGTTTGCTTTGAAAAAGG hCT2273636-Ex40-1 TTCATGTGAGCAGGTATGCTG TGCCATATTTAACTGCCATTTC TGAGCAAAACCTGTGGAATG hCT2273636-Ex40-2 TTGTGTACGACCCTCTGGTG TGCCATATTTAACTGCCATTTC TTTGCTGGTGCTGTCTATGG hCT2273636-Ex41 TTTGTACAGTGGAGGCAACG GCAGTCACTGAGACAGCTTTTATC GGATGTGCAAAATGTTCTTCTG hCT7084-Ex17 CAGCTGGTTATGTGTGTTTATGG TAAGCATAGCCTCGGAGAAC GGGAGCAGGTGTTATTGATTG hCT7084-Ex18 TGTCCTCATGGTTGCTTTTC GGACCATTAATAGCTACCTTCCTG GGTGAGGAGTTTTCCCAAGC hCT7084-Ex19 CAGGGACATGCTATCCAAAG AGGCAAGACAACATATTTGAAAG AGCAGAGAGTTTGTTAATGTTTTTAG hCT7084-Ex20 TGGTGGAACTTGTGTTTTTCC AAGGGCTATGTGTCATTTTGTTC GCTGACTTCTATTGGGAGCATAC hCT7084-Ex21 TCATACGGTTTTGGCAGCTC CATCAAGCAAGCAAACAAATG CAGAGGTATGGTTTGGGTCTC hCT7084-Ex22 ACAGAGGGAGAAGGGCTCAG AATTCCCCCAAAAGCTTCC TGGGGGTCTAGGACTATGGAG hCT7084-Ex23 TGGGACAATTTCGCAGAAG TTCCCTCCTGGCTAAGAACC GCTGTGTTTTCTTAATTTCCTGTATG hCT7084-Ex24-1 ATGAAAGCATGCTGCCTGATG AAAAGCAGAGGGAATCATCG CAGCCTCCTGCAGACTTTG hCT2257641-Ex1-56 GGGGGCCTTTAGAAGGAAG TCCCATTCATGACCTGGAAG CATTTTGGGAAAGGAGGTTC hCT2257641-Ex1-57 TGGAGTTCCTGAGAAATGAGC GGCCCGCTTTAAGAGATCAG CGGTCAGTATGACGGTAGGG hCT2257641-Ex1-58 AGAGGGAACACCCTTTCCTG CATGCCCAAAGTCGATCC AGGTCATGAATGGGATCCTG hCT2257641-Ex1-59 CATGATGTTGGAGCTTACATGC ACACATCCATGGTGTTGGTG GGCGCTAATCGTACTGAAAC hCT2257641-Ex1-60 CGGGATTGGAGACAGACATC TGCCACAGCCACATAGTCTC TATGGTGGCCATGGAGACTG hCT2257641-Ex1-61 CATCATGGTACACGCACTCC TTCTATCTGCAGACTCCCACAG AGGAGCCCTCCTTTGATTG hCT29277-Ex55 CTCAATCAGAGCCTGAACCAC GGAAAAGAAAGCAGGAGAAGC GGCCAGTGGTATCTGCTGAC hCT29277-Ex56 CCCGGCCTAAAGTTGTAGTTC AAATGGAGAAAAGCCTGGTTC AAGACAAAATCCCAAATAAAGCAG hCT29277-Ex57 TGGGAGACTGTCAAGAGGTG AAGCAATCCTCCCACCTTG ATTGGTTTGAGTGCCCTTTG hCT29277-Ex58 TTCCTCCAAGGAGCTTTGTC CCTTCCTTTTTCACTCACACAC AAAATGCTTTGCACTGACTCTG hCT29277-Ex59 TTCCCTGTCCAGACTGTTAGC TGATTTAATAATGAAGATGGGTTGG TTCATCTTTATTGCCCCTATATCTG hCT29277-Ex60 CCGGTTATGCACATCATTTAAG ACTCAGTACCCCAGGCAGAG TTAAAGATTATACCAAGTCAGTGGTC hCT29277-Ex61 GCAGCCAGAGCAGAAGTAAAC TCAAACTCCTGGGCTCAAAC CATGTGGTTTCTTGCCTTTG hCT29277-Ex62 TCTAATGAAAGCCCACTCTGC CAGCCACATCCCCCTATG AAGCATAGGCTCAGCATACTACAC hCT29277-Ex63 AAGTGTGCATGATGTTTGTTCC TGCCTTCTTCCACTCCTTTC CCCATCAACTACCATGTGACTG hCT29277-Ex64-1 GATGACCAAGAATGCAAACG AAGAGTGAAAGCAGAGATGTTCC GGTCCTGTTGTCAGTTTTTCAG NM_005026 Ex17 ATCATCTTTAAGAACGGGGATGG ACTAAGCCTCAGGAGCAGCCT GGTCCTGGGGTGCTCCTAGA NM_005026 Ex18 CCTCAGATGCTGGTGCCG GATACTTGGGGAAGAGAGACCTACC TCCTCAACTGAGCCAAGTAGCC NM_005026 Ex19 TCTTCATGCCTTGGCTCTGG GAGGGGAGAGGAGGGGGAG TGTGTCCTCCATGTTCTGTTGG NM_005026 Ex20 TCCGAGAGAGTGGGCAGGTA CACAAACCTGCCCACATTGC TGGCCCCTCTGCCTAGCA NM_005026 Ex21 GGGCAGGTTTGTGGGTCAT CCTGGGCGGCTCAACTCT CCACTGCTGGGTCCTGGG NM_005026 Ex22 GGAACTGGGGGCTCTGGG AGGCGTTTCCGTTTATGGC GAATAGAGAGCTTTTCCTGAGATGC hCT1640694-Ex1-1 GTTTCTGCTTTGGGACAACCAT CTGCTTCTTGAGTAACACTTACG GATTCATCTTGAAGAAGTTGATGG hCT1640694-Ex1-2 CTCCACGACCATCATCAGG GATTACGAAGGTATTGGTTTAGACAG ACTTGATGCCCCCAAGAATC hCT1640694-Ex1-3 CCCCCTCCATCAACTTCTTC GGTGTTAAAAATAGTTCCATAGTTCG CTCAAGAAGCAGAAAGGGAAG hCT1640694-Ex2-1 TCATCAAAAATTTGTTTTAACCTAGC TATAAGCAGTCCCTGCCTTC TCTACAGAGTTCCCTGTTTGC hCT1640694-Ex2-2 TTCTGAACGTTTGTAAAGAAGCTG TATAAGCAGTCCCTGCCTTC GCTGTGGATCTTAGGGACCTC hCT1640694-Ex3-1 GCAGCCCGCTCAGATATAAAC CTGGGCGAGAGTGAGATTCC AAAAAGCATTTCTGATATGGATAAAG hCT1640694-Ex3-2 TCTGAAAATCAACCATGACTGTG ATGAACCCAGGAGGCAGAG TCGAAGTATGTTGCTATCCTCTG hCT1640694-Ex4-1 TCTTGTGCTTCAACGTAAATCC CGGAGATTTGGATGTTCTCC AAAATAATAAGCATCAGCATTTGAC hCT1640694-Ex4-2 TCTCAACTGCCAATGGACTG CGGAGATTTGGATGTTCTCC TTATTCCAGACGCATTTCCAC hCT1640694-Ex5 TAGTGGATGAAGGCAGCAAC TTTGTAGAAATGGGGTGTTGC TTTGAGTCTATCGAGTGTGTGC hCT1640694-Ex6 TGCCTTTTCCAATCAATCTC AATTCCTGAAGCTCTCCCAAG TTCCTGTTTTTCGTTTGGTTG hCT1640694-Ex7 GGGGAAAAAAGGAAAGAATGG TGCTGAACCAGTCAAACTCC TGAATTTTCCTTTTGGGGAAG hCT1640694-Ex8 TTTGCTGAACCCTATTGGTG TTGCAATATTGGTCCTAGAGTTC TGGATCAATCCAAATAAAGTAAGG hCT1640694-Ex9 GATTGGTTCTTTCCTGTCTCTG CCACAAATATCAATTTACAACCATTG TTGCTTTTTCTGTAAATCATCTGTG hCT1640694-Ex10 ACCTTTTGAACAGCATGCAA TGGAAATAATGTTAAGGGTGTTTTT TATTTCATTTATTTATGTGGAC hCT1640694-Ex11 AAAACACCCTTAACATTATTTCCATAG TCTGCATGGCCGATCTAAAG GAAGTTAAGGCAGTGTTTTAGATGG hCT1640694-Ex12 TTATTCTAGATCCATACAACTTCCTTT AAAGTTGAGAAGCTCATCACTGGTAC ACCAGTAATATCCACTTTCTTTCTG hCT1640694-Ex13 CTGAAACTCATGGTGGTTTTG TGGTTCCAAATCCTAATCTGC TTTATTGGATTTCAAAAATGAGTG hCT1640694-Ex14 GAGTGTTGCTGCTCTGTGTTG TTGAGGGTAGGAGAATGAGAGAG TCTCATGTGAGAAAGAGATTAGCAG hCT1640694-Ex15 GGATTCCTAAATAAAAATTGAGGTG CATGCATATTTCAAAGGTCAAG TGGCTTTCAGTAGTTTCATGG hCT1640694-Ex16 TTGCTTTCCTGAAGTTTCTTTTG TCAAGTAAGAGGAGGATATGTCAAAG CATGTGATGGCGTGATCC hCT1640694-Ex17 GGGGAAAGGCAGTAAAGGTC CATCAAATATTTCAAAGGTTGAGC AGGAATACACAAACACCGACAG hCT1640694-Ex18 TCCTTATTCGTTGTCAGTGATTG GTCAAAACAAATGGCACACG TGCACCCTGTTTTCTTTTCTC hCT1640694-Ex19 CATGGTGAAAGACGATGGAC TTACAGGCATGAACCACCAC TGGACAAGTAATGGTTTTCTCTG hCT1640694-Ex20-1 TGGGGTAAAGGGAATCAAAAG CCTATGCAATCGGTCTTTGC TGACATTTGAGCAAAGACCTG hCT1640694-Ex20-2 TTGCATACATTCGAAAGACC GGGGATTTTTGTTTTGTTTTG TTGTTTTGTTTTGTTTTT ¹SEQ ID NO: 6 to 165 (forward primers) ²SEQ ID NO: 166 to 325 (reverse primers) ³SEQ lED NO: 326 to 485 (sequencing primers)

Example 2 This Example Demonstrates the Striking Clustering of Mutations within the PIK3CA Gene

All coding exons of PIK3CA were then analyzed in an additional 199 colorectal cancers, revealing mutations in a total of 74 tumors (32%) (Table 3 and examples in FIG. 1).

TABLE 3 PIK3CA mutations in human cancers Tumor type^(#) PIK3CA mutations* Functional Medullo- Exon Nucleotide Amino acid domain Colon GBM Gastric Breast Lung Pancreas blastomas Adenomas Total Exon 1 C112T R38C p85 1 1 Exon 1 G113A R38H p85 2 2 Exon 1 G263A R88Q p85 1 1 Exon 1 C311G P104R p85 1 1 Exon 1 G317T G106V p85 1 1 Exon 1 G323C R108P p85 1 1 Exon 1 del332-334 delK111 1 1 Exon 2 G353A G118D 1 1 Exon 2 G365A G122D 1 1 Exon 2 C370A P124T 1 1 Exon 4 T1035A N345K C2 1 1 Exon 4 G1048C D350H C2 1 1 Exon 5 T1132C C378R C2 1 1 Exon 7 T1258C C420R C2 2 2 Exon 7 G1357C E453Q C2 1 1 Exon 9 C1616G P539R Helical 1 1 Exon 9 G1624A E542K Helical 9 1 10 Exon 9 A1625G E542G Helical 1 1 Exon 9 A1625T E542V Helical 1 1 Exon 9 G1633A E545K Helical 21 1 22 Exon 9 A1634G E545G Helical 1 1 Exon 9 G1635T E545D Helical 1 1 Exon 9 C1636A Q546K Helical 5 5 Exon 9 A1637C Q546P Helical 1 1 Exon 12 C1981A Q661K Helical 1 1 Exon 13 A2102C H701P Helical 1 1 Exon 18 G2702T C901F Kinase 1 1 2 Exon 18 T2725C F909L Kinase 1 1 Exon 20 T3022C S1008P Kinase 1 1 Exon 20 A3073G T1025A Kinase 1 1 Exon 20 C3074A T1025N Kinase 1 1 Exon 20 G3129T M1043I Kinase 2 2 Exon 20 C3139T H1047Y Kinase 2 2 Exon 20 A3140G H1047R Kinase 15 2 1 18 Exon 20 A3140T H1047L Kinase 1 1 Bran 20 G3145A G1049S Kinase 1 1 Tumors with mutations 74 4 3 1 1 0 0 2 No. samples screened 234 15 12 12 24 11 12 76 Percent of tumors with mutations 32% 27% 25% 8% 4% 0% 0% 3% *Exon number with nucleotide and amino acid change resulting from mutation. Nucleotide position refers to position within coding sequence, where position 1 corresponds to the first position of the start codon. Functional domains are described in FIG. 1 legend. ^(#)Number of non-synonymous mutations observed in indicated tumors. Colon, colorectal cancers; GBM, glioblastomas; gastric, gastric cancers; breast, breast cancers; lung, lung cancers; pancreas, pancreatic cancers; medulloblastomas; adenomas, benign colorectal tumors. All mutations listed were shown to be somatic except for five colorectal cancers and one glioblastoma where no corresponding normal tissue was available. Mutations were identified in 58 of 201 mismatch repair (MMR) proficient colorectal cancers, and 16 of 33 MMR-deficient colorectal cancers. Some tumors with PIK3CA mutations contained mutations in KRAS or BRAF while others did not, suggesting that these genes operate through independent pathways. Seven tumors contained two somatic alterations. In addition to the 92 nonsynonymous mutations recorded in the table, we detected 3 synonymous alterations.

Example 3 This Example Demonstrates that the Mutations in PIK3CA Occur Late in Tumorigenesis

To determine the timing of PIK3CA mutations during neoplastic progression, we evaluated 76 pre-malignant colorectal tumors of various size and degree of dysplasia.

Only two PIK3CA mutations were found (E542K and E542V), both in very advanced adenomas greater than 5 cm in diameter and of tubuluvillous type. These data suggest that PIK3CA abnormalities occur at relatively late stages of neoplasia, near the time that tumors begin to invade and metastasize.

Example 4 This Example Demonstrates that PIK3CA Mutations in a Variety of Different Cancer Types

We then evaluated PIK3CA for genetic alterations in other tumor types (Table 1). Mutations were identified in four of fifteen (27%) glioblastomas, three of twelve (25%) gastric cancers, one of thirteen (8%) breast, and one of twenty four (4%) lung cancers. No mutations were observed in eleven pancreatic cancers or twelve medulloblastomas. In total, 89 mutations were observed, all but 3 of which were heterozygous.

Example 5 This Example Demonstrates the Non-Random Nature of the Genetic Alterations Observed

The sheer number of mutations observed in PIK3CA in five different cancer types strongly suggests that these mutations are functionally important. This conclusion is buttressed by two additional independent lines of evidence. First, analysis of the ratio of non-synonymous to synonymous mutations is a good measure of selection during tumor progression, as silent alterations are unlikely to exert a growth advantage. The ratio of non-synonymous to synonymous mutations in PIK3CA was 89 to 2, far higher than the 2:1 ratio expected by chance (P<1×10⁻⁴). Second, the prevalence of non-synonymous changes located in the PI3K catalytic and accessory domains was ˜120 per Mb tumor DNA, over 100 times higher than the background mutation frequency of nonfunctional alterations observed in the genome of cancer cells (P<1×10⁻⁴) (9).

Although the effect of these mutations on kinase function has not yet been experimentally tested, their positions and nature within PIK3CA imply that they are likely to be activating. No truncating mutations were observed and >75% of alterations occurred in two small clusters in exons 9 and 20 (Table 2 and FIG. 1). The affected residues within these clusters are highly conserved evolutionarily, retaining identity in mouse, rat, and chicken. The clustering of somatic missense mutations in specific domains is similar to that observed for activating mutations in other oncogenes, such as RAS (10), BRAF (11, 12), β-catenin (13), and members of the tyrosine kinome (14).

These genetic data suggest that mutant PIK3CA is likely to function as an oncogene in human cancers.

Example 6 This Example Demonstrates that Gene Amplification of PIK3CA is not Common

Quantitative PCR analysis of PIK3CA in 96 colorectal cancers showed no evidence of gene amplification, suggesting that gene copy alterations are not a significant mechanism of activation in this tumor type. The primers used were:

-   -   Real time PI3K hCT1640694 20-1F (intron)

TTACTTATAGGTTTCAGGAGATGTGTT; (SEQ ID NO: 486)

-   -    and     -   Real time PI3K hCT1640694 20-1R

GGGTCTTTCGAATGTATGCAATG (SEQ ID NO: 487)

The Sequence Listing appended to the end of this application contains the following sequences:

-   -   SEQ ID NO: 1=coding sequence only (nt 13 to 3201 of SEQ ID NO:         2)     -   SEQ ID NO: 2=RNA sequence (NM_(—)006218)     -   SEQ ID NO: 3=protein sequence (NP_(—)006209)     -   SEQ ID NO: 4=exon 9     -   SEQ ID NO: 5=exon 20     -   SEQ ID NO: 6 to 165=forward primers     -   SEQ ID NO: 166 to 325=reverse primers     -   SEQ ID NO: 326 to 485=sequencing primers     -   SEQ ID NO: 486 and 487 amplification primers

REFERENCES AND NOTES

-   1. R. Katso et al., Annu Rev Cell Dev Biol 17, 615-75 (2001). -   2. I. Vivanco, C. L. Sawyers, Nat Rev Cancer 2, 489-501 (July,     2002). -   3. W. A. Phillips, F. St Clair, A. D. Munday, R. J. Thomas, C. A.     Mitchell, Cancer 83, 41-7 (Jul. 1, 1998). -   4. E. S. Gershtein, V. A. Shatskaya, V. D. Ermilova, N. E.     Kushlinsky, M. A. Krasil'nikov, Clin Chim Acta 287, 59-67     (September, 1999). -   5. B. Vanhaesebroeck, M. D. Waterfield, Exp Cell Res 253, 239-54     (Nov. 25, 1999). -   6. S. Djordjevic, P. C. Driscoll, Trends Biochem Sci 27, 426-32     (August, 2002). -   7. Catalytic subunits of PI3Ks were identified by analysis of     InterPro (IPR) PI3K domains (IPR000403) present within the Celera     draft human genome sequence. This resulted in identification of 15     PI3Ks and related PI3K genes. The kinase domain of PIK3CD gene was     not represented in the current draft of human genome sequence and     was therefore not included in this study. -   8. Sequences for all annotated exons and adjacent intronic sequences     containing the kinase domain of identified PI3Ks were extracted from     the Celera draft human genome sequence (URL address: www host     server, domain name celera.com). Celera and Genbank accession     numbers of all analyzed genes are available in Table 1. Primers for     PCR amplification and sequencing were designed using the Primer 3     program (URL address: http file type, www-genome.wi.mit.edu host     server, cgi-bin domain name, primer directory, primer3_www.cgi     subdirectory), and were synthesized by MWG (High Point, N.C.) or IDT     (Coralville, Iowa). PCR amplification and sequencing were performed     on tumor DNA from early passage cell lines or primary tumors as     previously described (12) using a 384 capillary automated sequencing     apparatus (Spectrumedix, State College, Pa.). Sequence traces were     assembled and analyzed to identify potential genomic alterations     using the Mutation Explorer software package (SoftGenetics, State     College, Pa.). Of the exons extracted, 96% were successfully     analyzed. Sequences of all primers used for PCR amplification and     sequencing are provided in Table S1. -   9. T. L. Wang et al., Proc Natl Acad Sci USA 99, 3076-80. (2002). -   10. J. L. Bos et al., Nature 327, 293-7 (1987). -   11. H. Davies et al., Nature (Jun. 9, 2002). -   12. H. Rajagopalan et al., Nature 418, 934. (2002). -   13. P. J. Morin et al., Science 275, 1787-90 (1997). -   14. A. Bardelli et al., Science 300, 949 (May 9, 2003). -   15. J. Li et al., Science 275, 1943-7 (1997). -   16. P. A. Steck et al., Nat Genet. 15, 356-62 (1997). -   17. T. Maehama, J. E. Dixon, J Biol Chem 273, 13375-8 (May 29,     1998). -   18. M. P. Myers et al., Proc Natl Acad Sci USA 95, 13513-8 (Nov. 10,     1998). -   19. L. Shayesteh et al., Nat Genet. 21, 99-102 (January, 1999). -   20. J. Q. Cheng et al., Proc Natl Acad Sci USA 89, 9267-71 (Oct. 1,     1992). -   21. L. Hu, J. Hofmann, Y. Lu, G. B. Mills, R. B. Jaffe, Cancer Res     62, 1087-92 (Feb. 15, 2002). -   22. J. Luo, B. D. Manning, L. C. Cantley, Cancer Cell 4, 257-62     (2003). 

1. A method of assessing cancer in a body sample of a human suspected of having a cancer, comprising the steps of: determining presence of a non-synonymous, intragenic mutation in a PIK3CA coding sequence in the body sample, wherein a wild-type PIK3CA coding sequence comprises the sequence shown in SEQ ID NO:2; identifying the human as likely to have cancer if the presence of a non-synonymous, intragenic mutation in PIK3CA coding sequence is determined in the body sample.
 2. The method of claim 1 wherein the body sample is a first tissue that is suspected of being neoplastic, and the method further comprises the steps of: testing a second tissue that is not suspected of being neoplastic for the presence of the non-synonymous mutation, wherein the first and second tissue are isolated from the human; identifying the non-synonymous, intragenic mutation as somatic if said mutation is absent in the second tissue.
 3. The method of claim 1 wherein the non-synonymous, intragenic mutation is in exon 9 (SEQ ID NO: 4).
 4. The method of claim 1 wherein the non-synonymous, intragenic mutation is in exon 20 (SEQ ID NO: 5).
 5. The method of claim 1 wherein the non-synonymous, intragenic mutation is in PIK3CA's helical domain (nucleotides 1567-2124 of SEQ ID NO: 2).
 6. The method of claim 1 wherein the non-synonymous, intragenic mutation is in PIK3CA's kinase domain (nucleotides 2095-3096 of SEQ ID NO: 2).
 7. The method of claim 1 wherein the non-synonymous, intragenic mutation is in PIK3CA's P85BD domain (nucleotides 103-335 of SEQ ID NO: 2).
 8. The method of claim 1 wherein the body sample is colorectal tissue.
 9. The method of claim 1 wherein the body sample is brain tissue.
 10. The method of claim 1 wherein the body sample is gastric tissue.
 11. The method of claim 1 wherein the body sample is breast tissue.
 12. The method of claim 1 wherein the body sample is lung tissue.
 13. The method of claim 1 wherein the body sample is blood, serum, or plasma.
 14. The method of claim 1 wherein the body sample is sputum.
 15. The method of claim 1 wherein the body sample is saliva.
 16. The method of claim 1 wherein the body sample is urine.
 17. The method of claim 1 wherein the body sample is stool.
 18. The method of claim 1 wherein the body sample is nipple aspirate.
 19. The method of claim 1 wherein PIK3CA exons consisting of 9 and 20 are tested to determine a non-synonymous mutation.
 20. The method of claim 1 wherein PIK3CA exons comprising 9 and 20 are tested to determine a non-synonymous mutation.
 21. The method of claim 1 wherein the non-synonymous, intragenic mutation is a substitution mutation.
 22. The method of claim 21 wherein the body sample is further tested for mutations G113A, T1258C, G3129T, and C3139T.
 23. The method of claim 1 wherein the non-synonymous, intragenic mutation is G1624A.
 24. The method of claim 1 wherein the non-synonymous, intragenic mutation is G1633A.
 25. The method of claim 1 wherein the non-synonymous, intragenic mutation is C1636A.
 26. The method of claim 1 wherein the non-synonymous, intragenic mutation is A3140G.
 27. The method of claim 1 wherein the body sample is tested for mutations at nucleotide positions 1624, 1633, 1636, and 3140 of PIK3CA coding sequence.
 28. The method of claim 1 wherein the body sample is tested for mutations G1624A, G1633A, C1636A, and A3140G.
 29. The method of claim 28 wherein the body sample is further tested for mutation G2702T.
 30. The method of claim 1 wherein the non-synonymous, intragenic mutation is a deletion mutation.
 31. A method of characterizing a cancer in a body sample of a human, comprising the steps of: testing the body sample to determine the presence of a non-synonymous, intragenic mutation in a PIK3CA coding sequence in the body sample, wherein a wild-type PIK3CA coding sequence comprises the sequence shown in SEQ ID NO:2.
 32. The method of claim 31 wherein the body sample is a first tissue that is suspected of being neoplastic, and the method further comprises the steps of: testing a second tissue that is not suspected of being neoplastic for the presence of the non-synonymous mutation, wherein the first and second tissue are isolated from the human; identifying the non-synonymous, intragenic mutation as somatic if said mutation is absent in the second tissue.
 33. The method of claim 31 further comprising: identifying the human as likely to have cancer if a non-synonymous intragenic mutation in PIK3CA coding sequence is determined present in the body sample.
 34. The method of claim 31 further comprising: prescribing a therapeutic regimen based on the presence of the non-synonymous, intragenic mutation.
 35. The method of claim 31 wherein progression of disease is followed by the testing of the body sample.
 36. The method of claim 31 wherein the non-synonymous, intragenic mutation is in exon 9 (SEQ ID NO: 4).
 37. The method of claim 31 wherein the non-synonymous, intragenic mutation is in exon 20 (SEQ ID NO: 5).
 38. The method of claim 31 wherein the non-synonymous, intragenic mutation is in PIK3CA's helical domain (nucleotides 1567-2124 of SEQ ID NO: 2).
 39. The method of claim 31 wherein the non-synonymous, intragenic mutation is in PIK3CA's kinase domain (nucleotides 2095-3096 of SEQ ID NO: 2).
 40. The method of claim 31 wherein the non-synonymous, intragenic mutation is in PIK3CA's P85BD domain (nucleotides 103-335 of SEQ ID NO: 2).
 41. The method of claim 31 wherein the body sample is colorectal tissue.
 42. The method of claim 31 wherein the body sample is brain tissue.
 43. The method of claim 31 wherein the body sample is gastric tissue.
 44. The method of claim 31 wherein the body sample is breast tissue.
 45. The method of claim 31 wherein the body sample is lung tissue.
 46. The method of claim 31 wherein the body sample is blood, serum, or plasma.
 47. The method of claim 31 wherein the body sample is sputum.
 48. The method of claim 31 wherein the body sample is saliva.
 49. The method of claim 31 wherein the body sample is urine.
 50. The method of claim 31 wherein the body sample is stool.
 51. The method of claim 31 wherein the body sample is nipple aspirate.
 52. The method of claim 31 wherein PIK3CA exons consisting of 9 and 20 are tested to determine a non-synonymous mutation.
 53. The method of claim 31 wherein PIK3CA exons comprising 9 and 20 are tested to determine a non-synonymous mutation.
 54. The method of claim 31 wherein the non-synonymous, intragenic mutation is a substitution mutation.
 55. The method of claim 31 wherein the non-synonymous, intragenic mutation is G1624A.
 56. The method of claim 31 wherein the non-synonymous, intragenic mutation is G1633A.
 57. The method of claim 31 wherein the non-synonymous, intragenic mutation is C1636A.
 58. The method of claim 31 wherein the non-synonymous, intragenic mutation is A3140G.
 59. The method of claim 31 wherein the body sample is tested for mutations at nucleotide positions 1624, 1633, 1636, and 3140 of PIK3CA coding sequence.
 60. The method of claim 31 wherein the body sample is tested for mutations G1624A, G1633A, and A3140G.
 61. The method of claim 60 wherein the body sample is further tested for mutations C1636A, G113A, T1258C, G3129T, and C3139T.
 62. The method of claim 61 wherein the body sample is further tested for mutation G2702T.
 63. The method of claim 31 wherein the non-synonymous, intragenic mutation is a deletion mutation. 